Update requestProfiling javadoc

Update generally for better understandability, as well as adding  note about delay when starting profiling,
and option to stop early and stop for better control.

Bug: 345224246
Test: presubmit
Flag: EXEMPT - javadoc
Change-Id: I4fe66e48721a1ceba00f5cab925b74c54d762ced
1 file changed